Touch screen technologies have completely changed the way humans interact with different systems and their use is prevalent in several sectors, including the consumer market (mobile phones, tablets, etc.), the automotive industry, the banking sector, and the medical sector. Users can interact with the display by using their fingertips in a variety of single and multi-touch gestures.
Despite the popularity of touch screen technologies, their use within the cockpit environment of modern civil aircraft, as a method of interacting with avionic systems, is still relatively new. The majority of interactions between pilots and the various aircraft systems still take place via devices such as knobs, switches and keypads located mainly on the glare shield and on the central pedestal of an aircraft's flight deck. However, with the development of larger displays and the introduction of more avionics functionality in the cockpit, there has been a greater drive by industry to introduce touch screen functionality into the cockpit.
Several airlines have introduced Electronic Flight Bags (EFB)—which are implemented on tablet devices—in order to eliminate the paperwork that was previously carried by pilots.
On a majority of civil aircraft, autopilot commands (such as airspeed, altitude and heading settings) are input via the Flight Control Unit (FCU) on Airbus® aircraft and the Mode Control Panel (MCP) on Boeing® aircraft. These interfaces consist essentially of buttons, switches and knobs. For instance, on an Airbus® aircraft, in order to set a target value for altitude using such interfaces, the pilot first changes the guidance mode from ‘Managed’ (in which case the altitude is managed by the Flight Management System (FMS) according to a pre-defined flight plan) to ‘Selected’ (in which case the altitude is selected by the pilot). This change is achieved by pulling the altitude knob. The pilot then selects the target altitude by turning the knob clockwise to a higher altitude and anticlockwise to a lower altitude. The selected value and autopilot mode is then confirmed by cross-checking the corresponding annunciation made via the Flight Mode Annunciator (FMA) on the Primary Flight Display (PFD). It is possible to have a mixture of guidance modes where some parameters are ‘Managed’ whereas the rest are ‘Selected’.
The current state-of-the-art methods of interacting with the autopilot (and with other aircraft systems) work well and are very reliable. However, they have a number of drawbacks. For example, buttons, switches and knobs need to be distinct, that is, one device has one function. The large number of functions that need to be accessed by the pilot results in a large space needed for buttons, switches and knobs in the cockpit. This results in such devices being located all around the pilot, which is sub-optimal and, in certain cases, even being out of reach of the pilot and he or she will need to get out of the seat to reach the specific device.
Most buttons, switches and knobs are typically located in the glare shield, the main instrument panel, the central pedestal and the overhead panel, requiring the pilot to reach out to operate them. Locating the correct input control and selecting the desired option or value (such as entering a target altitude value in the FCU) can be relatively time-consuming, which is of significance particularly in high workload periods of the flight. This is inconvenient, especially when actions also involve relatively long operation times and careful selection (such as the selection of a specific large altitude change on the MCP/FCU). The situation is further compounded when the pilot needs to reach out to operate the device in turbulence conditions, as this makes the action much more difficult to execute correctly.
Also, input devices (such as the control panels and keypads) are expensive pieces of equipment that get damaged and need replacing during the life of the aircraft.
There are other limitations of using buttons, switches and knobs to control the aircraft. For example, their location may be sub-optimal due to constraints in the space available around the pilot. For example, the MCDU of an FMS is located by the pilot's knee which, although acceptable, would not be preferred if the pilot could instead have the device in front of him or her. Furthermore, buttons, switches and knobs may be located remotely from the display relating to their function. It is not advantageous to have controls and indicators related to the same function located remotely from each other. For example, the displays relating to the aircraft systems such as the fuel, hydraulic and electrical systems are normally located in the central part of the main instrument panel, whilst the switches and buttons controlling them are located on the overhead panel.
The location and use of buttons, switches and knobs may also limit the aircraft to need to be operated by two crew members under normal operating conditions. This may be for various reasons, including pilot workload.